math
posted by al on .
solve with substitution
5x  y=1
15x=2y

solve the first equation for y.
5xy=1 subtract 5x from both sides
y=15x divide by 1
y=1+5x
now, plug this answer in for y in the second equation.
15x=2y
15x=2(1+5x)
15x=2+10x
5x=2
x=.4
plug this(x=.4) into the equation for y.
y=1+5x
y=1+5(.4)
y=1+2
y=2
therefore, x=.4 and y=2 or (.4, 2) 
actually that does not work out, plug x and y into original equation...

actually that does not work out, plug x and y into original equation...
y=1+2
y=3
then it works out